Corvette Engine Build - The Power Principal, Part 2

We continue with our Econo 383 build

On the first installment of our 383 engine build, we covered the rotating assembly. Now we'll put the finishing touches on the engine assembly so we can install it. we wrapped up Part 1 by handling the clearance issues with the cam and rods. Now the cam timing should be checked. We're concerned with maximum power potential, and cam timing is critical.

Most things in life are a balance-when you make a performance gain you lose somewhere else. Cam timing is no different. Retarding the cam typically makes more power at high-rpm and makes the idle choppy. Advancing the cam allows better low-rpm throttle response and hurts horsepower at the big end. This is where our Virtual Engine dyno software came in handy. We could advance or retard the camshaft to see power gains and losses. Be careful to look over the entire rpm band, watching for the changes in horsepower and torque when cam timing is adjusted.

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We lubed our Comp Cams retro-fit hydraulic roller lifters with our Royal Purple assembly lube before installing them into the lifter bores. We didn't soak the lifters before installing them per Comp Cams recommendations. In the old days, you had to soak the lifters in oil overnight to let them fill up but no more. We plan on priming the oil system before installing the distributor to ensure complete system oiling before start-up.

To start, you need to be sure the cam timing is correct according to the camshaft manufacturer, then make changes if desired. There are many informative web sites that discuss cam timing. Take the time to read the theory and then put it into practice. Today's cam manufacturers have precise equipment that is rarely incorrect, but a slight indexing error will make cam timing off. It could be multiple things, including crankshaft index, cam gear, crank gear, or even timing chain variations, causing cam timing errors.

There are also other factors to consider. For instance, in our engine build, the Keisler-supplied, Tremec five-speed with 3:27:1 First gear, along with 10.4 compression, and the 3:73 rear axle ratio allows us to benefit from some cam retard to help top-end power. If we had an automatic transmission with a 1,400-rpm stall speed torque converter and 2:59 rear gear, advancing the cam would be in order to give some off-the-line zip. To ensure our cam would stay in perfect timing for many hours of engine operation, we used a Comp Cams High-Tech Roller Race timing set; Comp Cams pushrods and rocker arms actuate the valves with precision at high rpm.

Now the timing chain cover is on we could cover up the bottom end, but we had concerns about oil capacity. There aren't many alternatives when it comes to extra-capacity oil pans, especially in the '84-'86 Corvette cast-iron cylinder head engines. These early C4 engines have the two-piece crankshaft rear main seal, leaving these engines in an oil-pan quagmire that no one wanted to deal with. That is until Canton Racing Products stepped up and custom-built a Road Race oil pan with adequate ground clearance. The Canton oil pan has an 8-quart oil capacity and a built-in windage tray with the same 7-inch depth as the original GM pan. Canton now offers the oil pan in one- and two-piece rear seal versions with the dipstick on the right or left side. For those of you that have the later '91-'96 L-98 and LT engines, you can also use their pan since they provided a provision for the oil level sensor. The original clunky Delco starter can also be used.

Moving on to the valvetrain-smallblock cylinder head design has become huge over the last few years. We all know that combustion engines are air compressors. Efficient air flow equates to power gains. Edelbrock Performer RPM aluminum cylinder heads (PN 60999) completely assembled had been purchased previously for this project, so all we had to do was clean them for installation. The Edelbrock cylinder heads have 64cc combustion chambers with 2.02-intake and 1.60-exhaust valves, allowing .575 valve lift, so an aggressive lift camshaft can be used. GM D-port heads will coil bind at .495 valve lift in most cases when using stock components. Always check for valvespring coil bind and piston-to-valve interference, no matter what the numbers say.

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Corvette Engine Build - The Power Principal, Part 2

We lubed our Comp Cams retro-fit hydraulic roller lifters with our Royal Purple assembly lube before installing them into the lifter bores. We didn't soak the lifters before installing them per Comp Cams recommendations. In the old days, you had to soak the lifters in oil overnight to let them fill up but no more. We plan on priming the oil system before installing the distributor to ensure complete system oiling before start-up.

Now we check our cam timing by checking as the intake starts to rise and then before it returns to the base circle of the cam. We could use up a few pages just on cam timing and the theory behind it. Contacting Comp Cams and ordering their video on the procedure that walks you through the entire process is the best policy. One more thing-if you change the cam timing, recheck the connecting-rod-to-cam-lobe clearance. The cam lobes can be closer to the connecting rods when cam-timing changes are made.

Our Edelbrock Performer rpm cylinder head was temporarily installed with a weak valvespring to check our Comp Cams 1.6-ratio, high-tech, stainless steel rocker arms for proper rocker-arm geometry and piston-to-valve clearance. We watch the rocker arms roller tip during its full travel, making sure it stays centered on the valve. We also check for a minimum 0.050 piston-to-valve clearance.

This is how we check for proper pushrod length. Our Comp Cams adjustable pushrod length is manipulated until proper geometry is achieved. Once we have the correct length figured out, we measure the pushrod, and in most cases, Comp Cams has the specific length already built unless it's not a typical engine build. Be sure to check both intake and exhaust pushrods for proper length before ordering pushrods.

After we installed our timing cover, the Canton oil pump pick-up and screen was installed on the GM ZZ4 oil pump. The Canton screen has a built-in retainer that bolts to the oil-pump cover to prevent the screen from falling off, plus a tab is provided on the tube to easily tap the tube and screen assembly into the oil pump.

Our Canton oil pan cleared the connecting rods at the oil-pan rail, but the windage-tray tab on the side of the pan had connecting-rod interference that required a little massaging with our small hammer. We applied some assembly grease to the connecting rods and then installed the oil pan to see where the rods hit. Even if the connecting rods don't touch audibly, you should still check them with grease to make sure they aren't too close.

Next, the Edelbrock Performer cylinder heads are bolted on and then torqued to 65 lb-ft. We start from the center bolts and work outward, torqueing the bolts to 45 lb-ft on the first pass, then go back over them in the same pattern and finish at the prescribed 65 lb-ft. The two-step head bolt tightening sequence is not in any manual but it works. After years of assembling many engines without gasket failure, we do it that way every time.

Adjusting the Comp Cams stainless steel roller rocker arms correctly is important and tricky when the lifters aren't pumped up with oil. Once zero lash is found, while the camshaft lobe is at the base circle, 1 1/2 clockwise turns of the lock nut is required. Setting the valves too loose beats up the valve stem; too tight and burned valves can result.

The intake manifold base is now bolted in place, then all the retaining bolts are torqued to the correct specification. We use Teflon pipe sealer on all threads that retain the cylinder heads and intake manifold to prevent water and oil leaks out the bolt threads. The same technique of low-bolt torque then final-bolt torque is used when tightening to allow the gaskets to position themselves evenly without tearing.

Right before we drop the engine in the car, the Fluidamper balancer is installed with our Mac Tools harmonic balancer installer. We chose the Fluidamper balancer because of its extraordinary vibration control. the small diameter of the Fluidamper balancer for the Eagle crankshaft allows plenty of clearance at the crossmember.

We drop the engine in place easily because the manual transmission will be installed from the bottom. Once the engine and transmission are secure, our ancillary components are installed. As you can see, we spent a lot of time cleaning and painting before the engine was set in place.

We prefer to finish up the installation of the components from the bottom first. We slid our TPIS headers in from the bottom and are now placing the Earl's exhaust seals in place. We've had no complaints using the Earl's exhaust seals, even after 75,000 miles, no loose header bolts.

With our bottom-end components in place, the intake is assembled next. We ran an 8mm-1.25 tap through the lower intake runner bolt threads, and then installed the lower intake runner bolts on both sides. Accel slotted the lower intake runner mounting bosses to allow the runners to drop in place. This intake is a puzzle-install the wrong piece at the wrong time, and it has to come back apart to correct the sequence.

Our Bosch EV1 fuel injector is at the top of the photo. Although the external features of these injectors look similar, that's where it ends. Bosch stamps their build number on the upper injector body. This number correlates to fuel delivery and injector design. The clone injector has a painted number on the lower steel case with no stamping on the plastic upper body.

This is where things get sticky. The lower runners are in place, and we install the injector rail in place. Before you install the fuel-rail bolts, the fuel-supply lines should be connected. Once the fuel rail is in place and tightened, we can install the lower runner retaining bolts. This is also the time to think about your wiring. We decided to run our FAST injector wiring down the center of the intake before we covered things up.

Start every runner bolt at the manifold before tightening any bolt. Leave all the lower runner bolts loose until the plenum is installed. This particular Allen wrench with a ball socket on one end came with the Accel intake assembly to ease bolt tightening in many tight spots. The valve covers are left off during manifold assembly to access the lower runner bolts.

We connected our Bosch EV1 fuel injectors before we put our huge Accel plenum in place and then started tightening bolts. Remember to tighten all the bolts coming in from the underside for the plenum. We go around tightening the lower bolts of the plenum, making two passes to ensure all the upper and lower bolts are tightened properly. You can see just how tight the injectors and wiring are between the lower runners.

To finalize the intake-runner and plenum assembly, safety wire is applied to the plenum interior bolts. Don't let any fasteners get loose and drop into the runners. If that happens, these engine killers will be directed into the cylinder like a pinball machine. We keep tabs on the hardware, and if we can't find a particular bolt we stop and locate it before we proceed.

Our upper plenum cover is now installed, making two or three passes on the fasteners to ensure even load is applied. We also installed our TPIS 52mm throttle body to complete our intake system. Make sure to check for clearance issues at the wiper motor. We had to do a little machining to provide proper clearance. Unfortunately, we realized that later and then had to disassemble and re-assemble the throttle body.

You get to use just about every tool you own when you're working on a project like this. Here we're using our NAPA-supplied, W-crimp wire crimpers to install the idle air control valve wire terminals on our FAST computer wire harness. Make sure that you choose the correct crimp size and each wire is securely crimped.

Before we install our Performance Distributors LiveWires onto our Bosch spark plugs, a dab of silicone grease is applied into the plug boot and at the distributor. Performance Distributors warns that their warranty will not be valid if you rip the wires up trying to remove them if the silicone is not applied.

Our FAST fuel-injection system requires a MAP sensor to sense engine vacuum and control fuel delivery. We put our MAP sensor close to the vacuum source at the rear of the intake. The ideal location has the MAP sensor hose going down to the intake. This prevents oil from entering the hose causing erroneous vacuum readings.

Before we install our Performance Distributors computer-controlled distributor in place for good, we install it and tighten it down. Then we pull up and push down on the rotor and shaft assembly. This ensures that with all of our block machining the distributor won't be bound up sitting tight on the oil-pump driveshaft. Performance Distributors has shims available if necessary to keep the correct clearances.

Right before we start the engine, our oil-pump primer is used to build oil pressure. We run the drill clockwise until resistance is felt on the oil pump, then we look at the rockers arms watching for oil flow at each rocker. We also crank the engine a few revolutions, then run the primer again until all the rockers have oil flow.

Finally, we install our Performance Distributor and LiveWires on the distributor cap and start it up. We're using Performance Distributors billet wire looms to separate the extreme plug wires. The looms work easily and positively retain the wires. The LiveWires have easily read numbers at the distributor and plug end for quick installation-a nice touch on Corvettes that are hard to trace from the distributor.

The final touch is our Mini VIP voltage intensifier installation at the distributor. Just a couple of wires are necessary. We're using the original distributors pink wire that supplies ignition power. We need to connect the orange wire to the battery, then the black wire to ground. We'll be able to bump up our fuel pressure with the intense spark supplied from the Performance Distributors complete ignition system. Next time, we dyno the engine.